Zepbound for Weight Loss
Eli Lilly's weight loss shot. Patients in the largest clinical trial lost an average of 22.5% of their body weight, the most of any FDA-approved weight loss drug.
Reviewed by GlobalGLP1 editorial team • Drug facts last checked August 2026 • Sources: FDA prescribing information, peer-reviewed clinical trials
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Overview
Zepbound is a weekly injection from Eli Lilly that helps you lose weight by reducing appetite and slowing how fast your stomach empties. The FDA approved it in November 2023 for adults whose weight is affecting their health. It uses the same active ingredient as Mounjaro (which is approved for type 2 diabetes), but Zepbound is the version specifically labeled for weight loss. In the main study (called SURMOUNT-1), people on the highest dose lost about 22.5% of their starting body weight over about 17 months. For a 200-pound person, that's roughly 45 pounds. In December 2024 the FDA also approved Zepbound for moderate to severe obstructive sleep apnea in adults with obesity, the first prescription medicine ever approved for that condition, which matters for coverage as much as for breathing.
How Zepbound Works
Zepbound works by activating two hunger-related hormones at once: GIP and GLP-1. Most older weight loss medications only target one. By hitting both, Zepbound reduces appetite more effectively, slows digestion, and changes how your body stores fat. You take it as a once-weekly shot (usually in the belly, thigh, or upper arm). This dual approach is why Zepbound beat Wegovy 2.4 mg in SURMOUNT-5, the only trial that gave both drugs to comparable groups at the same time. It has never been tested against the higher 7.2 mg dose of Wegovy.
FDA Approval
Zepbound
Chronic weight management
2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg weekly injection
Zepbound
Moderate to severe obstructive sleep apnea in adults with obesity
10 mg or 15 mg weekly injection
How You Take It
Each dose step lasts at least 4 weeks. The slow build-up reduces stomach side effects. Some people get great results at 5 mg or 10 mg without needing the highest dose. Your doctor will help you find the right level.
How Much Weight You Can Lose
In the main weight loss trial, people on the highest dose (15 mg) lost an average of 22.5% of their body weight over about 17 months, estimated assuming everyone stayed on treatment. Counting everyone who started, the average was 20.9%. In SURMOUNT-5, the only trial that gave both drugs to comparable groups at the same time, Zepbound beat Wegovy 2.4 mg by 20.2% to 13.7% over 72 weeks. The newer higher-dose Wegovy HD has never been tested against Zepbound. Counting everyone who started, it averaged 18.7% over 72 weeks in its own trial (20.7% if everyone had kept taking it). Those figures come from separate trials with different people, so they cannot show which drug works better. About half of participants on 15 mg lost at least 20% of their body weight. For a 200-pound person, 22.5% is roughly 45 pounds. Lower doses also work: 5 mg averaged about 15% and 10 mg averaged about 19.5%. Results vary a lot from person to person.
Side Effects
Common Side Effects
- Nausea (about 29% of users at the 15 mg dose in SURMOUNT-1; usually worst during dose increases and eases over time)
- Diarrhea (about 23% of users; typically mild and short-lived)
- Decreased appetite (common; this is part of how the drug works)
- Vomiting (about 13% of users; tends to drop off after the first month or two)
- Constipation (about 12% of users)
- Abdominal pain (about 10% of users; usually mild)
- Indigestion / upset stomach (about 9% of users)
- Injection site reactions (uncommon; mild redness near the shot)
Rare but Serious
- Pancreatitis (rare)
- Gallbladder disease
- Thyroid C-cell tumors (boxed warning, rodent studies)
- Hypoglycemia (with insulin or sulfonylureas)
- Severe GI events
- Allergic reactions including anaphylaxis
- Breathing food or liquid into the lungs during surgery under general anesthesia or deep sedation. These drugs slow the stomach down, so tell your surgeon, anesthetist and dentist that you take one before any planned procedure
- Worsening of diabetic eye disease in people with type 2 diabetes who already have retinopathy. The label asks for monitoring; this is not described as a risk for people without diabetes
Managing side effects: Similar pattern to semaglutide: stomach-related side effects show up most during the first few weeks and around dose increases, then ease as your body adjusts. The slow dose build-up exists for this reason. Eating smaller, more frequent meals and avoiding high-fat foods help. If vomiting is persistent or severe, contact your provider. They can slow or pause the dose escalation.
Zepbound Cost & Savings (2026)
Savings programs: Zepbound Savings Card: commercially insured patients can pay as little as $25/month. LillyDirect Self Pay: cash-paying patients can buy the single-patient-use KwikPen or a 4-count single-dose vial direct from Lilly. Regular price for a 28-day supply is $299 (2.5 mg), $399 (5 mg), $499 (7.5 mg) and $699 (10 mg, 12.5 mg, 15 mg); a $449 purchase offer covers the first KwikPen fill at 7.5 mg and above and holds only while each refill purchase is completed within 45 days of your previous delivery, KwikPen only, through December 31, 2026.
Who Should Not Take Zepbound
- Personal or family history of a type of thyroid cancer called medullary thyroid carcinoma (MTC)
- A rare condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
- Allergy to tirzepatide or any ingredient in the medication
- Pregnancy or planning to become pregnant (stop at least 1 month before conception)
- Severe stomach or intestinal disease
What to Expect, Month by Month
Noticeable decrease in hunger and food noise. Some patients report reduced cravings for high-calorie foods specifically.
Consistent weight loss begins during dose escalation. Average 3-5% body weight lost. Dual GIP/GLP-1 action accelerates early results.
Approaching maintenance dose (10-15 mg). Steady 1-2.5 lbs per week loss. Blood sugar improvements prominent.
Average 15-20% body weight lost. Dramatic improvements in metabolic health markers, blood pressure, and lipids.
Weight loss plateau at 20-22.5% average. Some patients achieve 25%+ loss. Maintenance phase with sustained metabolic benefits.
Other Medications to Watch
Can cause dangerously low blood sugar when combined. Your doctor will likely reduce your insulin dose by 20 to 50% when starting tirzepatide, and may also lower your sulfonylurea dose.
Because tirzepatide slows digestion, pills you take by mouth may absorb differently. This is most noticeable during the first few months when dose changes are happening and stomach effects are strongest.
Slower digestion can change how warfarin absorbs. Your doctor should check your clotting levels (INR) more often when starting or changing your tirzepatide dose.
The FDA label tells prescribers to advise anyone on birth control pills to switch to a non-oral method, or add a barrier method such as condoms, for 4 weeks after starting and for 4 weeks after each dose increase. In testing, tirzepatide cut peak blood levels of the hormones in a combined pill by more than half. Tirzepatide may cause fetal harm. Methods that are not swallowed, such as the patch, ring, implant, injection or IUD, are not affected.
Special Situations
Do not use during pregnancy; the label says to stop as soon as a pregnancy is known. Unlike semaglutide, whose label sets a two-month gap before trying to conceive, the tirzepatide label sets no such period, so ask your prescriber how long to stop beforehand. Animal studies showed harm to the fetus at high doses.
No dose change needed at any level, including end-stage kidney disease, where blood levels of tirzepatide were unchanged. Still watch for dehydration from nausea and vomiting, which can worsen kidney function on its own.
No dose change needed at any level. Blood levels of tirzepatide did not change in people with liver impairment.
No dose change needed. The Zepbound trials included 226 people aged 65 or older, 13 of them 75 or older. Slower dose increases may help reduce stomach side effects in older adults.
Not yet FDA-approved for adolescents. Clinical trials in teens (SURMOUNT-TEENS) are in progress. Some doctors prescribe it off-label for teens with severe obesity.
What Happens If You Stop
In the SURMOUNT-4 trial, people who stopped tirzepatide after 36 weeks regained about two-thirds of the weight they had lost over the following year. People who stayed on it continued to lose weight. This is why most doctors recommend staying on treatment long-term if it is working.
How to make stopping easier: Building healthy eating habits and regular exercise while on the medication is the best insurance against regain. Some doctors are exploring lower maintenance doses to keep weight off at lower cost. Start planning your long-term approach before stopping.
Zepbound FAQs
Zepbound and Mounjaro are the same drug (tirzepatide) at the same doses, just sold under different names for different uses. Mounjaro is the version approved for type 2 diabetes. Zepbound is the version approved for weight loss. Your doctor will prescribe whichever one matches your situation, and your insurance is likely to cover only the one that fits your diagnosis.
Lilly lists Zepbound at $499 to $1,086.37 per fill depending on the product and dose (its price to wholesalers, as of January 1, 2026), and defines a monthly supply as 28 days. Most cash-paying patients do not pay that. Lilly sells direct through LillyDirect Self Pay as a single-patient-use KwikPen or a 4-count single-dose vial, not the single-dose Pen. The regular self-pay price for a 28-day supply is $299 at 2.5 mg, $399 at 5 mg, $499 at 7.5 mg, and $699 at 10 mg, 12.5 mg and 15 mg. A $449 purchase offer applies automatically to your first KwikPen fill at 7.5 mg or above, and keeps applying only if each refill purchase is completed within 45 days of your previous delivery; it covers the KwikPen only, is capped at 11 fills a year and ends December 31, 2026. One thing to plan around: 2.5 mg is a starting dose and is not approved as a maintenance dose, so work from the price of the dose you expect to stay on rather than the lowest figure.
It depends on the dose. In the main clinical trial, people on the 5 mg dose lost about 15% of their starting body weight on average. The 10 mg dose averaged about 19.5%, and the highest 15 mg dose averaged 22.5% over roughly 17 months. About half of patients on the 15 mg dose lost at least 20% of their body weight. Results vary a lot from person to person depending on diet, exercise, and how your body responds.
It can, and it is worth asking about. In December 2024 the FDA approved Zepbound for moderate to severe obstructive sleep apnea in adults with obesity, based on the SURMOUNT-OSA trial, where people averaged about 25 fewer breathing interruptions an hour. It was the first prescription medicine approved for OSA at all. This matters because plenty of plans refuse to pay for weight loss but will pay to treat sleep apnea, which they treat as a medical condition rather than a lifestyle one. State Medicaid programs are required to cover a drug for its approved indications, and moderate to severe OSA is now one of the approved indications for Zepbound. You do need a sleep study confirming the diagnosis. If your plan has already turned you down for weight loss and you snore, wake up unrefreshed, or your partner has noticed you stop breathing at night, raise it with your doctor.
It depends on your plan. Many large commercial insurance plans now cover Zepbound, but they usually require prior authorization. That means your doctor has to send paperwork showing you qualify (typically a BMI of 30 or higher, or 27+ with another weight-related health condition). Standard Medicare Part D still does not cover drugs used only for weight loss. Since July 1, 2026, a temporary program called the Medicare GLP-1 Bridge has covered the Zepbound KwikPen for eligible people with obesity at $50 a month, through December 31, 2027. It has its own eligibility rules, and the single-dose vials and pens are not included. Use the clinic directory below to find providers that accept your insurance.
You need a prescription from a licensed doctor or nurse practitioner. You can get one in person or through a telehealth clinic, and many telehealth providers offer same-week video appointments. Use the directory below to compare clinics in your state that prescribe Zepbound, including their prices, telehealth options, and insurance accepted.
The most common side effects are stomach-related: nausea, diarrhea, vomiting, constipation, and stomach pain. They usually show up when you first start or move up to a higher dose, and most people find they get better after a few weeks. Rare but more serious risks include inflammation of the pancreas, gallbladder problems, and a warning about thyroid tumors (seen in animal studies, not confirmed in humans). Always tell your doctor about your full medical history before starting.
Yes, and it's common. Head-to-head studies show Zepbound (tirzepatide) tends to produce more weight loss than Wegovy or Ozempic (semaglutide) on average. Your doctor will usually start you on the lowest Zepbound dose (2.5 mg) when you switch, even if you were on a high dose before, so your body can adjust and you don't get hit with stomach side effects. Don't switch on your own. Talk to your prescriber first.
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References
Every figure on this page comes from one of the following. Prescribing information is linked on DailyMed, which serves the current label rather than a snapshot of an old one. Trials are linked by DOI.
- Zepbound (tirzepatide) injection: prescribing information
- Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1) The 72-week weight-loss trial behind the ~21-22.5% figures.
- Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5) The only head-to-head trial of the two, and the fairest comparison of them.
Drug facts on this page last checked against these sources August 2026.
Medical Disclaimer: This guide is for informational purposes only and is not medical advice. All clinical data is sourced from FDA prescribing information and published peer-reviewed trials. Individual results vary. Always consult a qualified healthcare provider before starting, stopping, or switching any medication.